First off, you're furbabies already know what's happening and that a new addition is comming soon. They have a greater advantage than us with not only instinct, but with heightened smell.
It's like this, you come home with a nice juicy burger w/the works, they go wild because they are overwhelmed by ALL the individual smells. They don't smell the burger as a whole like we do, they smell each and every different component to that burger, meat, each spice, onions, tomato, baccon, cheese, catsup, mayo, pickles, and bun! That is why they get so excited, they are bombarded with all these wonderful smells...LOL
So you have an advantage, you're furbabies already know
you're preggy and have accepted that fact. You can involve them by teaching them how to be caregivers too, like fetching diapers, wipes, burp rags, blankies, and so on.
You have so many little helpers that are more than willing to help out, it's never too late to teach a new duty to our babies.
My friend even taught her babies to "find the binkie" which came in handy as those are always getting lost...LOL
on you're new addidion, keep us updated!